Considering how many people eat too much and exercise too little, it's not surprising that nearly 67 million Americans have high blood pressure. But here's the asterisk: 36 million of them do not have it under control, even though most know they have the disease and, often, have medication for it.

What gives? The Centers for Disease Control and Prevention, which released these statistics in a "Vital Signs" report that covered 2003 to 2010, said driving the gap is a string of "missed opportunities," from patient neglect, to lax doctor counseling, to failed teamwork by health care workers.

Yes, uncontrolled hypertension is highest among people who do not have doctors or health insurance, or are poor or uneducated.

"But most people who have it go to doctors and have insurance," said Amy Valderrama, lead author of the study and epidemiologist with the CDC's Division for Heart Disease and Stroke Prevention. "That includes 17 million well-educated (have attended or graduated from college) people and more than 7 million in the highest income bracket."

Although seniors are more likely to have hypertension, the largest group with uncontrolled hypertension is ages 18 to 24. Seniors are more likely to take their medication.

Hypertension is blood pressure of 140/90 or higher. For every increase of 20 of the systolic (first) number or 10 of the diastolic (second) number, the risk of heart disease and stroke double, said the CDC report. That is starting from a base of 115/75.

Left unchecked, hypertension contributes to heart disease and strokes, which the CDC said are the first and fourth leading causes of death. This adds $131 billion to our collective health-care costs each year.

"Hypertension is known as the silent killer because you may not have any symptoms," said Dr. Steven Fox, internist at Advocate Illinois Masonic Medical Center in Chicago. "You don't know you have it, so you necessarily don't go to the doctor."

"Men are notorious for not going," said Samantha Mok, cardiology social worker with Rush University Medical Center in Chicago. "Often, their wives call to make their appointments. And women tend to put everyone else in their families first and themselves last."

Both genders are guilty of denial, added Mok. "People just want to ignore it," she said.

Even though side effects of hypertension medications are uncommon, said Fox, they worry many patients. They include dry cough and fatigue, but the one that scares off the most patients is impotence, he said.

"If that happens, the patient may just quit taking the medication and not talk to his doctor about it," said Fox. "But if he does tell us, we may be able to try something else. Or, we try a combination of medications."

Others just neglect their prescriptions because they see no gain, said Fox. "With something like arthritis, you take your medicine and you feel better," he said. "With hypertension, you feel the same."

Noncompliance is not for lack of availability. Most pharmacies offer free blood-pressure checks. Big-box retailers sell popular hypertension medications at discounted prices. Wal-Mart, for example, sells a 30-day supply of Atenolol for $4. "People don't know this," said Mok of the population she serves. Even fewer know about the drug manufacturers' freebies for low-income people, she added.

Meanwhile, too many Americans continue to eat high-fat and high-salt foods, lead sedentary lives and smoke cigarettes, which all contribute to hypertension, said Valderrama. Competing with Michelle Obama's "Let's Move" anti-obesity program are millions of dollars spent advertising junk food.

The CDC report said doctors, pharmacists and other health care workers need to work with the patients in a team-based approach to combat hypertension. But pharmacists have little contact with patients today and doctor visits are shorter.

So, what is the solution? "Doctors need to do a better job counseling patients about their lifestyles choices, then follow-up," said Fox. "This is a public health problem, with obesity, diabetes and hypertension going hand-in-hand ... we need to help people change their lifestyles."

Valderrama points to groups that are increasing public awareness of hypertension, such as Million Hearts, aimed at the public, and Team Up. Pressure Down, which targets pharmacists.

In the end, the patient is his own best advocate, said the experts. "Ask questions," said Mok. "Don't be intimidated. Understand the disease. Take your medicine."